Pulsation eliminator for rayon systems



May 8, 1934. R. H. McKEE-Z 1,958,009

PULSATION ELIMINATOR FOR RAYON SYSTEMS Filed Dec. 25, 1929 F20 PUMP r0 inn/50:;

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A TTORNE V Patented May 8, I934 PULSATION ELIMINATOR FOR RAYON SYSTEMS Ralph H. McKee, Jersey City, N. J Application December 23, 1929, Serial No. 415,987 3 Claims. (Cl. 137-71) The present invention relates to pulsation length of 10 feet in the path of the spinning eliminators for rayon pumps, and more particusolution between the pump and the spinning larly to pulsation eliminators for smoothing the nozzle. It is considered that the viscosity of the flow of fluid from rayon pumps to the spinneret. spinning solution in this long tube plays the part 5 It is the common experience in the manufacof an absorber.

ture of rayon that there are pulsations in the An object of the present invention is to profiow of the fluid whether piston or gear pumps vide an apparatus and a method for overcomare used. By rayon I mean not only viscose and ing the shortcoming noted hereinabove. cuprammonium but also the cellulosenitrate and The invention also has within its contemplation cellulose acetate types of artificial silk. Except the provision of an apparatus and a method which 65 for the disadvantages of pulsations, the piston will practically eliminate the pulsations in the type of pump has advantages over the gear type flow of rayon liquid in a simple and practical both in operation and in life. However, the pismanner.

' ton type is particularly prone to give troublesome Other objects and advantages will become appulsations. Various schemes have been proposed parent from the following description taken in 70 to modify, calm down, and remove the pulsations conjunction 'with the accompanying drawing in which are objectionable because they produce which: v lack of uniformity in the rayon filaments as the Fig. 1 is an embodiment of my invention; latter issue from the spinneret. For instance, it Fig. 2 is a modified embodiment;

has been proposed to use 3, 4, 5, 6, or '7 plungers Fig. 3 shows a sectional view taken on the line 75 instead of the simple 1 or 2 plungers which might 3-3 of Fig. 2; otherwise be used. It is also quite common to Fig. 4 is a sectional view taken on the line 4-4 use a pressure bottle which acts as an air chamof Fig. 2;

ber just as does the air chamber of the old fash- Fig. 5 represents another modification of my 2 ioned force pump used for the pumping of water invention; and 80 by hand. In rayon manufacture this air cham- Fig. 6 depicts a sectional view taken on the line her is generally placed at the pump though in 6-6 of Fig. 5.

some cases it is placed in the line between the In accordance with the present invention, a

pump and the spinneret. It has the disadvantage new method and apparatus have been devised forthat the treatment of the solution with air under eliminating pulsations, whether they are caused 85 a pressure of say 200 pounds per square inch disby a piston pump or irregularities in the teeth of, solves the air in the solution and on the release a gear pump or from other cause. of the pressure at the spinneret this air tends Generally speaking, my invention contemplates to come out of solution and makes the resulting the interposition of a stabilizing device, such as a filaments irregular. Moreover, in course of time, pipe, receptacle, or the like having an expansible 90 due to the solution of the air in the liquid in the and compressible construction, between the pump air chamber, the latter fills up with this aerated and the.spinneret in the path of the spinning liquid and then ceases to be operative. In pracsolution. tice these air chambers are often spoken of as In Fig. 1 of the drawing I have illustrated a pressure bottles and are generally made of glass, preferred embodiment of my invention which con- Accordingly they are fragile and it is diflicult to sists of a fluted vessel V which is fluted in the same make a tight joint that will not leak under the way as a steam expansion joint is fluted, that is, pressure used. with a plurality of flutes F passing around the ex- Some attempts have been made to overcome pansion vessel. One end E of thesexpansion vesthe trouble of pulsations by having the spinning sel will be closed by means of an approximately 100 liquid pass through the threads of a screw in its flat plate and into the other end will be inserted path between the pump and the spinneret. This the inlet I and exit tubes 0. via inlet and outlet arrangement, however, does not effect adequate connections A and D respectively, the said inlet absorption of the pulsations. Moreover the and outlet tubes leading to the pump and spinminute opening in the screw is easily obstructed neret respectively. One of these tubes will reach 1 5 and, due to its minuteness, increases the already into the expansion vessel nearly its full length. high working pressure under which the rayon If thevessel is set above the pump it is the exit pump operates. An effort to improve this artube to the spinneret which will be the longer rangement consists in placing a tube having an tube just mentioned, that is, the expansion vessel internal diameter of approximately 5 mm. and a will be set so that it will be continuously full of the spinning solution. In this case pulsations will be taken up by the movements of the fluted portion together with the approximately flat surface at the end which does not carry the inlet and outlet tubes.

Still another embodiment of my invention is illustrated in Fig. 2 which consists of a flat sided tube U of elastic metal, say ordinary steel or chromium steel. Such a tube will expand with increased pressure and thereby take up the pulsations. This tube may be a straight tube, a helix or a coil although it is herein shown as made of a plurality of helical turns H. A tube of medium wall thickness whose internal bore is x inch and length is 24" wound in the form indicated is ample in most cases. In the case of a coil I prefer to wind it with the flat side G of the tube at substantially right angles -to the axis of the coil. In the case of a helix I prefer to make it a double helix as shown in Fig. 2, that is, the tube being wound about itself in one direction and then turned and wound back parallel to the originalturns with the flat side of the tube at approximately right angles to the axis of the helix. By the use of this helix, with each pulsation, the tube will expand and the helix itself will tend to open, that is, increase in diameter, and the pulsations thereby be removed. With the coil mentioned above I will obtain a similar effect by which the pulsations will be absorbed.

Another modification of my invention is illustrated in Fig. 5 wherein the reference character B designates a base plate to which my stabilizing device is secured. In the present instance, the device is fastened to the base plate B by means of a cover plate C and a plurality of bolts S. The inlet pipe I which comes from the pump leads to an inlet A. Between the inlet Aand the outlet D I interpose a coil pipe P constituted of a multiplicity of turns T. A cross section of the coil pipe may be clearly seen from Fig. 6 which illustrates the pipe as having a flat elliptical cross section. This pipe is capable of expanding and contracting when subject to variations in pressure. The construction is made compact by the pipe following a spiral curve from the inlet connection to a central portion and then bending back upon itself and forming another spiral which leads to the outlet connection D. From the outlet connection a pipe 0 conducts the rayon solution to a spinneret.

By interposing my stabilizing device between the inlet pipe coming from the pump and the outlet pipe 0 leading to the spinneret I am able to absorb and practically eliminate pulsations produced by .the pump or other variations in the pressure of the rayon solution. The stabilizing device absorbs and eliminates practically all of the pressure variations so that the fluid flowing through outlet pipe 0 to the spinneret is free from detrimental pulsations or variations in pressure.

It is to be noted that the present invention provides a pulsation eliminator which requires only a small volume of liquid between the pump and spinneret and yet, as this liquid is constantly flowing to the spinneret, there will be no dead spaces where, for example, viscose may become over-ripe and form material which would clog the tubes, the candle filter or the spinneret. Pressure bottles cannot and do not smooth out pulsations to more than a quite limited extent. They must be changed and cleaned every two or three days. This entails a stoppage of production as well as the labor of changing and cleaning the pressure bottles. With the present device the stoppage of production and the labor of substitution and cleaning are avoided while a continuous and even flow of spinning solution is obtained.

It is sometimes desirable at the time of starting to spin, by the dry spinning process, solutions carrying volatile solvents, such as cellulose acetate or cellulose nitrate solutions, to give a sudden increased pressure to the liquid with which the spinneret is fed. It has been proposed to use a single plunger pump to give this sudden pressure so that the solution will leave the face of the spinneret in the former threads rather than spread over the face of the spinneret. With the present device it will be sufiicient for the operator to press upon the helix or coil or fluted tube with his hand when this pressure increase of the solution is desired. Once the thread is started through the spinneret the pressure can be relieved and the device will operate as before mentioned for the removal of pulsations.

What is claimed is:-

1. In a rayon spinning system having a pipe line between a' pump and a spinneret that improvement which comprises a pressure equalizing device consisting of a flexible, non-rigid shell completely fllled with a viscous rayon spinning solution, said shell being constituted of a resilient metal capable of substantially unrestricted expansion and contraction and capable of absorbing shocks and pulsations and of eliminating practically all of the detrimental pressure variations, an inlet tube opening at the bottom of said shell and connecting with said pump for the delivery of pulsating viscous rayon spinning solution, and a separate outlet tube opening within the interior of said shell and adjacent to the top thereof for transmitting the viscous rayon solution flowing through said shell to the spinneret whereby pulsating viscous rayon solution flows continuously into said flexible metal shell which removes the pulsations and substantially equalizes the pressure and which imparts to the viscous rayon solution through the outlet tube to the spinneret a substantially uniform pressure, said flexible metal vessel, said inlet and said outlet being devoid oi. air chambers and spaces.

2. A rayon pulsation eliminator for systems carrying viscous rayon liquid which comprises a flexible, non-rigid vessel, completely filled with rayon liquid and through which rayon liquid continuously flows, said vessel being located in the pipe line between the pump and the spinneret and being constituted of a resilient metal capable of substantially unrestricted expansion and contraction and capable of absorbing shocks and pulsations and of eliminating practically all of the detrimental pressure variations, an inlet 35 connection secured to said device for introducing pulsating rayon liquid from the pump, and a separate outlet connection secured to said device for continuously removing rayon liquid therefrom, said metal vessel being substantially free 140 from dead spaces, whereby pulsating viscous rayon solution flows continuously into said flexible metal vessel which removes the pulsations and substantially equalizes the pressure and which imparts to the viscous rayon solution flowing continuously through the outlet tube to the spinneret a substantially uniform pressure, said flexible metal vessel, said inlet and said outlet being devoid of air chambers and spaces.

flowing continuously 120 secured to said vessel for continuously removing non-pulsating rayon liquid therefrom, said vessel being substantially free from 'dead end spaces and air spaces, whereby pulsating viscous rayon solution flows continuously into said flexible metal vessel which removes the pulsations and substantially equalizes the pressure, and which imparts to the viscous rayon solution flowing continuously through the outlet tube to the spinneret a substantially uniform pressure, said flexible metal fluid elements, inlet and outletbeing devoid oi." air chambers and spaces.

RALPH H. McKEE. 

